The expression of Candida albicans enolase is not heat shock inducible

Abstract An isoprotein of enolase from the yeast Saccharomyces cerevisiae was reported to be a heat shock protein. The possible role of the C. albicans enolase as a heat shock protein was therefore investigated. The de novo synthesis of C. albicans enolase protein and mRNA did not increase during heat stress, but remained constitutively expressed. Amino acid similarity to the heat shock proteins suggests that although the C. albicans enolase is not a classical heat shock protein, it may be a memberof a group of constitutively expressed, structurally related proteins, the heat shock cognate proteins.     

Structural principles for the propeller assembly of beta-sheets: the preference for seven-fold symmetry.

Twisted beta-sheets, packed face to face, may be arranged in circular formation like blades of a propeller or turbine. This beta-propeller fold has been found in three proteins: that in neuraminidase consists of six beta-sheets while those in methylamine dehydrogenase and galactose oxidase are composed of seven beta-sheets. A model for multisheet packing in the beta-propeller fold is proposed. This model gives both geometrical parameters of the beta-propellers composed of different numbers of sheets and patterns of residue packing at their sheet-to-sheet interfaces. All the known beta-propeller structures have been analyzed, and the observed geometries and residue packing are found to be in good agreement with those predicted by models. It is shown that unusual seven-fold symmetry is preferable to six- or eight-fold symmetry for propeller-like multi-sheet assembly. According to the model, a six-beta-sheet propeller has to have predominantly small residues in the beta-strands closed to its six-fold axis, but no strong sequence constraints are necessary for a seven-fold beta-propeller.     

A novel electroconductive interface based on Fe3O4 magnetic nanoparticle and cysteamine functionalized AuNPs: Preparation and application as signal amplification element to minoring of antigen‐antibody immunocomplex and biosensing of prostate cancer

In this study, a novel electroconductive interface was prepared based on Fe₃O₄ magnetic nanoparticle and cysteamine functionalized gold nanoparticle. The engineered interface was used as signal amplification substrate in the electrochemical analysis of antibody‐antigen binding. For this purpose, biotinilated‐anti‐prostate‐specific antigen (PSA) antibody was bioconjugated with iron oxide magnetic nanoparticles (Fe₃O₄) and drop‐casted on the surface of glassy carbon electrode (GCE). Also, secondary antibody (HRP‐Ab2) encapsulated on gold nanoparticles caped by cysteamine was immobilized on the surface of GCE modified electrode. A transmission electron microscopy images shows that a sandwich immunoreaction was done and binding of Ab1 and Ab2 performed successfully. Various parameters of immunoassay, including the loading of magnetic nanoparticles, the amount of gold nanoparticle conjugate, and the immunoreaction time, were optimized. The detection limit of 0.001 μg. L^?1 of PSA was obtained under optimum experimental conditions. It is found that such magneto‐bioassay could be readily used for simultaneous parallel detection of multiple proteins by using multiple inorganic metal nanoparticle tracers and are expected to open new opportunities for early stage diagnosis of cancer in near future.     

Misannotations of the genes encoding sugar N‐formyltransferases

Tens of thousands of bacterial genome sequences are now known due to the development of rapid and inexpensive sequencing technologies. An important key in utilizing these vast amounts of data in a biologically meaningful way is to infer the function of the proteins encoded in the genomes via bioinformatics techniques. Whereas these approaches are absolutely critical to the annotation of gene function, there are still issues of misidentifications, which must be experimentally corrected. For example, many of the bacterial DNA sequences encoding sugar N‐formyltransferases have been annotated as l ‐methionyl‐tRNA transferases in the databases. These mistakes may be due in part to the fact that until recently the structures and functions of these enzymes were not well known. Herein we describe the misannotation of two genes, WP_088211966.1 and WP_096244125.1, from Shewanella spp. and Pseudomonas congelans, respectively. Although the proteins encoded by these genes were originally suggested to function as l ‐methionyl‐tRNA transferases, we demonstrate that they actually catalyze the conversion of dTDP‐4‐amino‐4,6‐dideoxy‐d ‐glucose to dTDP‐4‐formamido‐4,6‐dideoxy‐d ‐glucose utilizing N¹⁰‐formyltetrahydrofolate as the carbon source. For this analysis, the genes encoding these enzymes were cloned and the corresponding proteins purified. X‐ray structures of the two proteins were determined to high resolution and kinetic analyses were conducted. Both enzymes display classical Michaelis–Menten kinetics and adopt the characteristic three‐dimensional structural fold previously observed for other sugar N‐formyltransferases. The results presented herein will aid in the future annotation of these fascinating enzymes.     

Identification and characterization of a new 34 kDa MORN motif-containing sporozoite surface-exposed protein,Cp-P34, unique to Cryptosporidium

Despite the public health impact of childhood diarrhea caused by Cryptosporidium, effective drugs and vaccines against this parasite are unavailable. Efforts to identify vaccine targets have focused on critical externally exposed virulence factors expressed in the parasite s invasive stages. However, no single surface antigen has yet been found that can elicit a significant protective immune response and it is likely that pooling multiple immune targets will be necessary. Discovery of surface proteins on Cryptosporidium sporozoites is therefore vital to this effort to develop a multi-antigenic vaccine. In this study we applied a novel single-domain camelid antibody (VHH) selection method to identify immunogenic proteins expressed on the surface of Cryptosporidium parvum sporozoites. By this approach, VHHs were identified that recognize two sporozoite surface-exposed antigens, the previously identified gp900 and an unrecognized immunogenic protein, Cp-P34. This Cp-P34 antigen, which contains multiple Membrane Occupation and Recognition Nexus (MORN) repeats, is found in excysted sporozoites as well as in the parasite s intracellular stages. Cp-P34 appears to accumulate inside the parasite and transiently appears on the surface of sporozoites to be shed in trails. Identical or nearly identical orthologs of Cp-P34 are found in the Cryptosporidium hominis and Cryptosporidium tyzzeri genomes. Except for the conserved MORN motifs, the Cp-P34 gene shares no significant homology with genes of other protozoans and thus appears to be unique to Cryptosporidium spp. Cp-P34 elicits immune responses in naturally exposed alpacas and warrants further investigation as a potential vaccine candidate.     

Incorporation of the Tat cell‐penetrating peptide into nanofibers improves the respective antitumor immune response

A major challenge for the development of anticancer vaccines is the induction of a safe and effective immune response, particularly mediated by CD8+ T lymphocytes, in an adjuvant‐free manner. In this respect, we present a simple strategy to improve the specific CD8+ T cell responses using KFE8 nanofibers bearing a Class I (Kb)‐restricted peptide epitope (called E. nanofibers) without the use of adjuvant. We demonstrate that incorporation of Tat, a cell‐penetrating peptide (CPP) of the HIV transactivator protein, into E. nanofibers remarkably enhanced tumor‐specific CD8+ T cell responses. E. nanofibers containing 12.5% Tat peptide (E.Tat_12.5 nanofiber) increased antigen cross‐presentation by bone marrow‐derived dendritic cells as compared with E. nanofibers, or E. nanofibers containing 25 or 50% the Tat peptide. Uptake of KFE8.Tat_12.5 nanofibers by dendritic cells (DCs) was significantly increased compared with KFE8 nanofiber lacking Tat. Peritoneal and lymph node DCs of mice immunized with E.Tat_12.5 nanofibers exhibited increased presentation of the H2kb‐epitope (reminiscent for cross‐presentation) compared with DCs obtained from E. nanofiber vaccinated mice. Tetrameric and intracellular cytokine staining revealed that vaccination with E.Tat_12.5 triggered a robust and specific CD8+ T lymphocyte response, which was more pronounced than in mice vaccinated with E. nanofibers alone. Furthermore, E.Tat_12.5 nanofibers were more potent than E. nanofiber to induce antitumor immune response and tumor‐infiltrating IFN‐γ CD8 T lymphocyte. In terms of cancer vaccine development, we propose that harnessing the nanofiber‐based vaccine platform with incorporated Tat peptide could present a simple and promising strategy to induce highly effective antitumor immune response.     

Evidence of egg-laying grounds for critically endangered flapper skate (Dipturus intermedius) off Orkney,UK

Essential fish habitats (EFHs) are critical for fish life-history events, including spawning, breeding, feeding or growth. This study provides evidence of EFHs for the critically endangered flapper skate (Dipturus intermedius) in the waters around the Orkney Isles, Scotland, based on citizen-science observation data. The habitats of potential egg-laying sites were parametrised as >20 m depth, with boulders or exposed bedrock, in moderate current flow (0.3–2.8 knots) with low sedimentation. This information provides a significant contribution to the understanding of EFHs for flapper skate.     

Evolution of herbs: key to the conundrum might be tolerance not avoidance

草本植物的进化：解决难题的关键在于忍耐而非逃避 木本植物延续了其祖先被子植物的生长形态,而草本植物则不断地从中进化演变。虽然关于驱动草本植物习性进化的因素已有许多假设,但是通过舍弃地上生物质从而避免冬季冻害的能力常常被认为是促使其进化的主要力量。然而,鉴于草本植物在反复干扰中依旧能够轻松存活,我们提出了不可预测的干扰可能比季节性霜冻更为重要的假设。我们通过比较草本植物和木本植物应对3种模拟干扰(容易预测的冬季冰冻、不易预测的春季冰冻和食草作用)的能力来验证这一假设。通过比较20种不同植物在同质园实验中的表现,我们评估了这些干扰对植物死亡和再生方面的影响。研究结果表明,在冬季冰冻条件下,比起木本植物,草本植物在存活率上并没有优势。在不易预测的春季冰冻条件下,草本植物比木本植物的存活率更高。而在模拟食草作用的条件下,草本植物的这种生存优势更大。在不可预测的条件下,草本植物相较于木本植物的生存优势表明,草本植物的生长形式可能是对不可预测的干扰的适应,这种逆境忍耐通过其损失地上生物质也能够生存的能力得以实现。因此,哺乳动物的食草行为或火灾等原因或许最有可能是木本植物向草本植物过渡的因素。